package NowCoderHuaWei;

import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Scanner;

public class Test09{
    public static void main(String[] args)
        {
        Scanner in=new Scanner(System.in);
        while(in.hasNext())
            {
            int n=in.nextInt();
            HashSet<Character>hs=new LinkedHashSet<Character>();
            String str=Integer.toString(n);
            for(int i=str.length()-1;i>=0;i--)
            {
            	hs.add(str.charAt(i));
            }
            for(char ch:hs)
            {
            	System.out.print(ch);
            }
        }
        in.close();
    }
}